Stitch control device in flat knitting machine

ABSTRACT

In a loop length controller for a flat knitting machine adapted to set adapted to set the loop length of a knitting fabric by raising or lowering, by a raising and lowering means, a stitch cam attached to a carriage that slides on a needle bed to slidably operate knitting needles forward and backward, the raising and lowering means is provided with a driving motor and a converting mechanism for converting the rotational motion of the driving motor into ascent and descent of the stitch cam, wherein the converting mechanism is configured such that the ascending and descending amount of the stitch cam with respect to the rotational amount of the driving motor differs between a side for a larger drawing-in amount of knitting needles for loops of longer length and a side for a smaller drawing-in amount of knitting needles for loops of shorter length.

TECHNICAL FIELD

[0001] The present invention relates to a controller for setting a loop length in a flat knitting machine.

BACKGROUND ART

[0002] As this type of stitch controller for a flat-knitting machine, there has been known the one described in, for example, Japanese Examined Patent Application Publication No. 6-94618 previously proposed by the present applicant.

[0003] According to the previously proposed one, as shown in FIG. 6 of the publication, a stitch cam of a carriage that slides on a needle bed to slide a knitting needle forward and backward is operated by oscillating the stitch cam connected to the distal end of the operating lever. The operating lever is oscillated up and down by means of a spiral cam groove of the stitch cam operating cam attached to an output shaft of a driving motor. The spiral cam groove of the stitch cam operating cam is configured such that the spacing from the center of the stitch cam operating cam is proportional to the rotational angle of the stitch cam operating cam, and the ascending and descending amount of the stitch cam is also proportional to the rotational angle of the stitch cam operating cam, as indicated by a two-dot chain line B in FIG. 4.

[0004]FIG. 1 in the publication shows one wherein the operating lever is oscillated by a stitch cam operating cam equipped with spiral threads.

[0005] The loop length available in one knitting machine is roughly decided by a gauge indicating the number of stitches per inch.

[0006] For example, in the case of a 16-gauge knitting machine, the interval (pitch) between adjoining needles is 1.5875 mm. In the case of an 8-gauge knitting machine, the pitch between knitting needles is 3.175 mm.

[0007] A sinker is provided between individual knitting needles of a needle bed, and the inter-sinker pitch is equal to the inter-needle pitch.

[0008] There are sinkers on both sides of a knitting needle, and the loop length is decided by how far the knitting needle is drawn in by a stitch cam.

[0009] Once a gauge is decided, then the pitch is decided accordingly. If, therefore, a knitting machine is designed to provide a stitch cam drawn-in amount that exceeds an appropriate range, then the sizes of loop length and yarn sizes will not match, making it unsuitable as a product. Thus, only yarns of sizes in a range suited for pitches can be used for making knitting fabrics.

[0010] Accordingly, in general knitting machines, the drawn-in amounts of stitch cams are set within an appropriate range for gauges. At the gauges, a bottom elastic or the like, for example, is knitted with loops of short length, while plaited patterns, such as a cable-stitch pattern, are knitted with loops of long length.

[0011] Recently, however, there has been increasing demand for “seamless knit” that saves a sewing step after a knitting step and also features improved fashionableness. For making the seamless knit, a tubular sweater having a front body and a back body joined on sides by a single knitting machine provided with needle beds at its front and back. To respond to the demand, seamless knits are made by skipped needle knitting in which every other knitting needles of the needle beds are used, the skipped needles being used for transferring stitches to knit the fabric. The skipped-needle knitting is carried out as described below.

[0012] For example, to knit a seamless sweater by the skipped-needle knitting by using a 16-gauge knitting machine, the pitch between knit stitches will be double the standard pitch. More specifically, the stitch pitch will be 8 gauges, and the drawn-in amount of a stitch cam must be increased to obtain an 8-gauge knit fabric.

[0013] The spiral cam groove of the foregoing stitch cam operating cam is designed such that the ascending and descending amount of the stitch cam is proportional to the rotational angle of the stitch cam operating cam. Hence, the skipped-needle knitting can be implemented simply by increasing the drawn-in amount; however, there is a problem in that the displacement amount of the stitch cam per step in the 16-gauge knitting is basically large, making it impossible to make finer adjustment of loop length.

[0014] As a solution, a step motor having a higher resolution could be used as a driving motor, while using the conventional cam design. This, however, leads to a problem of higher manufacturing cost because a step motor is expensive.

[0015] Especially a cam assembly of a knitting machine uses many driving motors. For instance, in a 3-cam knitting machine for making three courses by one travel of a carriage over a needle bed, a pair of right and left step motors are provided for one knitting unit, meaning that 3 cams×two (right and left)×front and rear carriages=12 step motors would be necessary. The one described in the above publication would require six step motors as well as drivers therefor.

[0016] The present invention has been proposed in view of the above problems, and it is an object of the invention to make it possible to provide a loop length controller in a flat knitting machine that permits highly accurate loop length control for knitting with a standard gauge and also permits satisfactory loop length control in a skipped-needle knitting mode without causing an increase in manufacturing cost.

DISCLOSURE OF INVENTION

[0017] To fulfill the above object, a loop length controller in a flat knitting machine in accordance with the present invention is designed to set the loop length of a knitting fabric by raising or lowering, by a raising and lowering means, a stitch cam attached to a carriage that slides on a needle bed to slidably operate knitting needles forward and backward, the raising and lowering means comprising a driving motor and a converting mechanism for converting the rotational motion of the driving motor into ascent and descent of the stitch cam, wherein the converting mechanism is configured such that the ascending and descending amount of the stitch cam with respect to the rotational amount of the driving motor differs between a side for a larger drawing-in amount of knitting needles for loops of longer length and a side for a smaller drawing-in amount of knitting needles for loops of shorter length.

[0018] Furthermore, the converting mechanism is equipped with an operating lever having one end thereof pivotally supported by a bottom board and the other end thereof connected to a stitch cam slidably guided by a raising and lowering slide slot, and a stitch cam operating cam provided on an output shaft of the driving motor, the operating lever has an engaging portion, and the stitch cam operating cam comprises a spiral track that slidably engages with the engaging portion, the track being shaped such that the ascending and descending amount of the stitch cam with respect to the rotational amount of the driving motor is larger for a side for a larger drawing-in amount of knitting needles, while the ascending and descending amount of the stitch cam with respect to the rotational amount of the driving motor is smaller for a side for a smaller drawing-in amount of knitting needles.

BRIEF DESCRIPTION OF THE DRAWINGS

[0019]FIG. 1 is a bottom view of a stitch cam portion of a carriage related to a loop length controller in a flat knitting machine in accordance with the present invention.

[0020]FIG. 2 is a top plan view of the stitch cam portion of the carriage related to the loop length controller in the flat knitting machine in accordance with the present invention.

[0021]FIG. 3 is a bottom view of a stitch cam operating cam related to the loop length controller in the flat knitting machine in accordance with the present invention.

[0022]FIG. 4 is a graph showing a relationship between loop length values and stitch cam descending amounts of the loop length controller in the flat knitting machine in accordance with the present invention.

[0023]FIG. 5 is a schematic top plan view showing another embodiment of a raising and lowering means related to the loop length controller in the flat knitting machine in accordance with the present invention.

[0024]FIG. 6 is a schematic top plan view showing still another embodiment of the raising and lowering means related to the loop length controller in the flat knitting machine in accordance with the present invention.

BEST MODE FOR CARRYING OUT THE INVENTION

[0025] The following will describe an embodiment related to a loop length controller in a flat knitting machine of the present invention in conjunction with the accompanying drawings.

[0026]FIG. 1 shows a group of cams of a carriage 2 provided on a bottom board 1, observed from bottom. A pair of stitch cams 4 and 4 is provided on both sides of a rasing cam 3, the stitch cams 4 and 4 are provided with raising and lowering means 5 and 5 for raising and lowering them, which will be discussed hereinafter.

[0027] The stitch cams 4 and 4 and the raising and lowering means 5 and 5 are disposed substantially linearly symmetrical, and share the same mechanism. Hence, one of the raising and lowering means 5 will be explained.

[0028] First, as shown in FIG. 1 and FIG. 2, a vertically diagonal raising and lowering slide slot 6 is drilled in the bottom board 1. A sliding member 7 is slidably fitted in the raising and lowering slide slot 6, the stitch cam 4 being located on the bottom surface thereof with the sliding member 7 sandwiched therebetween, while a holding plate 8 being secured on the top surface thereof integrally with the sliding member 7, so that the stitch cam 4 slides up and down along the raising and lowering slide slot 6.

[0029] Next, as shown in FIG. 2, the raising and lowering means 5 is constructed of a driving motor 9, a stitch cam operating cam 12 provided with a spiral cam groove (track) 11 which is attached to an output shaft 10 of the driving motor 9 and which will be discussed hereinafter, and an operating lever 14 oscillated by an engaging portion 13 that engages with the spiral cam groove 11. The spiral cam groove 11 and the operating lever 14 provided with the engaging portion 13 that slides by being guided by the cam groove 11 constitute a converting mechanism T.

[0030] The operating lever 14 is pivotally supported by a bracket 16 having a proximal end portion 15 mounted on the bottom board 1, has an engaging portion composed of a roller at a position near its middle, and has a long hole 18 at its distal end, the long hole 18 being closed by a spring 17.

[0031] A stopper projection 19 formed of a roller vertically provided on the top surface of the holding plate 8 is fitted in the long hole 18.

[0032] Furthermore, the stitch cam operating cam 12 is provided with a horn-shaped lug 20. The moment a proximity sensor (not shown) provided on the bottom board 1 detects the lug 20, it is regarded as position 0 and the driving motor 9 is stopped.

[0033] As shown in FIG. 2 and FIG. 3, the spiral cam groove 11 formed in the stitch cam operating cam 12 is convolutionally formed over about 330 degrees around the output shaft 10 of the driving motor 9.

[0034] At starting end position 0 where the proximity sensor detects the lug 20, the engaging portion 13 engaged with the spiral cam groove 11 reaches the position closest to the output shaft 10 of the driving motor 9. In other words, the stitch cam 4 rises to the highest point, forming loops of the shortest length.

[0035] At a terminating end position (the state shown in FIG. 2 and the position at 90 on the axis of abscissa shown in FIG. 4), the engaging portion 13 engaged with the cam groove 11 is at the farthest position from the output shaft 10 of the driving motor 9. In other words, the stitch cam 4 lowers to a lowest point, forming loops of the longest length. The cam groove 11, however, is shaped such that the ascending and descending amount of the stitch cam 4 with respect to the rotational amount of the driving motor 9 is not proportional during the travel from the starting end to the terminating end.

[0036] The shape of the cam groove 11 will now be explained in conjunction with FIG. 3 and FIG. 4.

[0037]FIG. 4 is a graph showing a relationship between loop length values (corresponding to the rational amounts of the driving motor 9) and stitch cam lowering amounts in a 16-gauge flat knitting machine used for knitting a seamless sweater by skipped-needle knitting. The axis of abscissa indicates the loop length values, while the axis of ordinate indicates the stitch cam lowering amounts. The cam groove 11 of the embodiment is denoted by A in the figure.

[0038] As shown in FIG. 3 and by A in FIG. 4, a proportion D1 at which the spiral cam groove 11 moves away from an axial center P of the output shaft 10 when the output shaft 10 of the driving motor 9 turns from the loop length value 10 to the loop length value 80 is set to provide a gentler slope than at a proportion D2 at which the spiral cam groove 11 moves away from an axial center P of the output shaft 10 when the output shaft 10 turns from the loop length value 0 to the loop length value 10 or the conventional straight line indicated by B in FIG. 4.

[0039] The gentler slope is set for the output shaft 10 of the driving motor 9 to revolve from the loop length value 10 to the value 80, as compared with the conventional straight line indicated by B in FIG. 4 or the remaining portions for the following reason. In the range of loop length values from 10 to 80, loops of shorter length are formed at the values in the vicinity of 10 when knitting at 16 gauge, while loops of longer length are formed at values in the vicinity of 80 when knitting at 8 gauge. Hence, the above gentler slope is set to permit relatively fine adjustment to be made for any cases within the aforesaid range.

[0040] Furthermore, from the loop length values 80 to 90, a proportion D3 at which the spiral cam groove 11 moves away from the axial center P of the output shaft 10 is set to have a larger rate of change than that of the proportion D2, forming a steep slope, as shown in FIG. 4. This allows the stitch cam to be drawn down to a maximum of the lowering amount usually used when the 16-gauge flat knitting machine is used as a 8-gauge flat knitting machine by skipped-needle knitting.

[0041] When applying the rate of change for the range from the loop length values 80 to 90 to the flat knitting machine used as the 8-gauge model, the stitch cam can be further drawn down beyond the aforesaid maximum of the lowering amount usually used by setting a larger proportion of the stitch cam lowering amount with respect to loop length values, as indicated by, for example, the dashed line or the one-dot chain line in FIG. 4.

[0042] Even if the rate of change in the vicinity of the maximum stitch cam lowering amount is increased when the flat knitting machine is used as the 8-gauge model, the loop length is still longer at 8 gauge than at 16 gauge, so that a difference caused by a slight increase in the displacement amount of the stitch cam will not show in the knitted fabric.

[0043] As indicated by reference character C in FIG. 4, the proportion of the stitch cam lowering amount with respect to the loop length values may be changed at two places in the vicinities of the loop-length values 45 and 60 so as to be formed of three straight lines having different slopes, or may be easily changed in a second order curve simply by changing the spiral shape of the cam groove 11, although it is not shown.

[0044] Furthermore, the raising and lowering means 5 in the above embodiment is constructed of a driving motor 9, the stitch cam operating cam 12 having the spiral cam groove 11 that is attached to the output shaft 10 of the driving motor 9, and the operating lever 14 having the engaging portion 13 engaged with the helical cam groove 11 to be oscillated; alternatively, however, a link type shown in FIG. 5 and FIG. 6 may be used.

[0045] In the raising and lowering means 5 shown in FIG. 5 and FIG. 6, the ratio of the stitch cam lowering amount with respect to loop length values changes in the second order curve. In the raising and lowering means 5 shown in FIG. 5, the output shaft 10 of the driving motor 9 and the holding plate 8 of the stitch cam 4 are connected by a jointed link 20 to form a converting mechanism T.

[0046] In the raising and lowering means 5 shown in FIG. 6, an operating lever 14 having a proximal end portion 15 thereof pivotally supported by the bottom board 1 and a distal end portion thereof connected to the holding plate 8 of the stitch cam 4 is operated by an operating stick 21 oscillated by the driving motor 9 so as to form the converting mechanism T.

[0047] In the embodiment described above, so-called “double gauge” in which a 16-gauge flat knitting machine is used for 8-gauge knitting by skipped-needle knitting has been taken as an example; the present invention, however, is not limited thereto.

[0048] In addition, according to the above embodiment, the spiral cam groove 11 forms the track for oscillating the operating lever 14. The spiral cam groove 11 may be replaced by, for example, the protuberant line shown in FIG. 1 of Japanese Examined Patent Application Publication No. 6-94618 previously proposed by the present applicant.

[0049] Furthermore, it is needless to say that the present invention can be implemented by using, a curve for the “riding slope surface of the control track” in, for example, Japanese Patent No. 2566200.

INDUSTRIAL APPLICABILITY

[0050] As explained above, the loop length controller in a flat knitting machine according to the present invention is constructed such that the ascending and descending amount of a stitch cam with respect to the rational amount of a driving motor differs between the side where the drawn-in amount of knitting needles is large to form loops of longer length and the side where the drawn-in amount of knitting needles is small to form loops of shorter length. Hence, fine adjustment can be made in standard knitting portions frequently used in knitting and in addition, loop length can be adjusted also in a portion wherein a loop length exceeds that of the loops of the shortest length or in the vicinity of the loops of the longest length.

[0051] For instance, the ascending and descending amount of a stitch cam with respect to the rotational amount of a driving motor can be changed simply by changing the shape or the like of a spiral track. For a longer loop, adjustment can be accomplished by increasing the increasing ratio of the displacement of a stitch cam to the rotational angle of the stitch cam operating cam without the need for increasing the resolution of a stitch cam control motor. For a shorter loop, fine adjustment can be made, while the adjustment range can be expanded for longer loops to permit an extended maximum loop length. This arrangement advantageously obviates the need for using an expensive step motor exhibiting a higher resolution, making it possible to prevent an increase in the manufacturing cost due to the expensive step motor. 

1. A loop length controller for a flat knitting machine adapted to set the loop length of a knitting fabric by raising or lowering, by a raising and lowering means, a stitch cam attached to a carriage that slides on a needle bed to slidably operate knitting needles forward and backward, the raising and lowering means comprising a driving motor and a converting mechanism for converting the rotational motion of the driving motor into ascent and descent of the stitch cam, wherein the converting mechanism is configured such that the ascending and descending amount of the stitch cam with respect to the rotational amount of the driving motor differs between a side for a larger drawing-in amount of knitting needles for loops of longer length and a side for a smaller drawing-in amount of knitting needles for loops of shorter length.
 2. The loop length controller for a flat knitting machine according to claim 1, wherein the converting mechanism comprises an operating lever having one end thereof pivotally supported by a bottom board and the other end thereof connected to a stitch cam slidably guided by a raising and lowering slide slot, and a stitch cam operating cam provided on an output shaft of the driving motor, the operating lever has an engaging portion, and the stitch cam operating cam comprises a spiral track that slidably engages with the engaging portion, the track being shaped such that the ascending and descending amount of the stitch cam with respect to the rotational amount of the driving motor is larger for a side for a larger drawing-in amount of knitting needles, while the ascending and descending amount of the stitch cam with respect to the rotational amount of the driving motor is smaller for a side for a smaller drawing-in amount of knitting needles. 